A ratchet tool of the prior art, as disclosed by U.S. Pat. No. 6,386,072, uses a switch to drive the left and right shift of a driving piece, which in turn drives a resilient pushing device to push a braking piece to engage another driving piece, whereby the wrench box can attain a forward and backward rotation. Further, a longitudinal supporting device within the wrench main body can be engaged with a locking portion of the driving piece to achieve a retaining effect of a ratchet wheel.
However, the ratchet wrench of the prior art lacks a basic function of producing noises in backward reposition for facilitating operation in the night time when visual recognition is not allowed.
In a conventional ratchet wrench, the braking piece is driven by the pushing unit disposed in the half-moon shaped rear portion of the retaining box of a ratchet wrench, which pushing unit consists of a resilient piece and a pushing piece and provide the reposition of the braking piece with a necessary force. Thereby, the driving part and the switch unit can be engaged, and, since a locking portion of the switch unit restricts the motion of the switch unit, the driving part of the wrench is accordingly locked, leading to a small spacing between a projected portion and a groove of the driving part for the braking piece to move. Therefore, the noises produced in a process of backward reposition are not loud enough for people operating it at night time hard to recognize such a reposition.
Further, a ratchet wrench of the prior art has a complex assembly process that includes a step of locking a buckle body within boundary groove around a cover, in addition to an orderly placement of the driving part and the braking body.